There are shortcuts in kicking competitors out of the markets through controlling resource demand
Elaborate.
also by selling cheaper than it produces until the competitors are stranged economically.
Yes, I talked about this. By undercutting the competitors, the company seeking a monopoly is weakened (they are not making a substantial profit). This gives new competition even more incentive to enter the market and compete, because they know it will be easier to compete with the weakened companyA.
Easy money! i have all the good squares, they stay, they pay! I would just take their money in the first round and in the second I would make them sell their squares to pay me more.
You're still thinking about this in terms of the game rather than reality.
I'll give you more realistic variables, then: Let's say people are fed up with the prices your monopolistic company is demanding, and as such society has harboured a feeling of general dislike towards your company. Now, when I said new players can enter the game whenever they like, I bet you though they could only enter with the starting amount of cash. No, that is an element of the game, not reality. In reality, new competition has however much cash investors want to invest in it. The society's dislike of your monopoly is a signal to investors to invest in competition. They see that it will be easy to compete, because no one wants to buy your shit. So they invest a truckload into the new competition, possibly even more than your monopoly's assets.
Now, tell me how you're going to just take their money in the first round?
life is not just the economy
The economy is an abstract concept that represents the actions of humans in relation to one another. Unless you live in a forest by yourself without any human contact, I would say economics is a very large part of life.
To think ahead, imagine ways to bring down oppression and make society fair, honest and equal for everyone and pave the way for it.
I would like to think that that's what I'm doing.